Surfacing — surfacing is the component that protects the weatherproofing and reinforcement from sunlight and weather. Some surfacings provide other benefits such as increased fire resistance, improved traffic and hail resistance, and increased solar reflectivity.

With some roof membranes, a component may perform more than one function.

Steep-slope roofing

There are six generic classifications of steep slope roof coverings. Click on a roof covering type for more information.

Roof deck — a roof deck is the structural substrate and usually is a wood-based material such as plywood or oriented strand board (OSB).

Underlayment — underlayment provides temporary protection until a roof covering is installed and provides a secondary weatherproofing barrier. Sometimes underlayment is referred to as “felt” or “paper.”

Roof covering — the roof covering is the external water shedding material.